Security chain

ABSTRACT

A door safety chain in which the slide track does not terminate at the end away from the edge of the door but re-enters the base, the slide track being notched to permit removal of the slide carrying the safety chain in a direction toward the door edge and at an angle to the track.

United States Patent [191 Schulz Mar. 12, 1974 S ECUR/ITY CHAIN3,275,364 9/1966 Quinn 292/264 [76'] In ento m d- Sc ulz 02 N. 118th3,705,504 12/1972 Johnson 70/93 St., Milwaukee, Wis. 53226 D PrimaryExaminer-Werner H. Schroeder Flled? 1972 Attorney, Agent, orFirmWheeler, Morsell, House & 21 Appl. No.: 312,020 Wheeler 52 us. ct.292/264 AB R ,[51] Int. Cl. E05c 17/36 d 7 oor safety cham m which theSildfi track does not [58] Field of Search 70/93, 292/264 terminate atthe end away from the edge of the door R f d but re-enters the base, theslide traek being notched to 1 t e erences permit removal of the slidecarrying the Safety chain in UNITED STATES PATENTS a direction towardthe door edge and at an angle to 2,087,755 7/1937 Dayton 292/264 thetrack. 2,867,468 [/1959 Bugge 3,126,220 3/1964 Callegari 292/264 7 6Claims, 6 Drawing; Figures PAltNtinlmzaeu 3796.450

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ll (W WW WWW"""W ZQ WH W' M BACKGROUND OF THE INVENTION The purpose ofthe invention is to provide additional safety against the activities ofhousebreakers. The traditional variety of safety chain slide track has aclosed end nearest the door frame and terminates at a free end which issecured so that it is remote from the door edge. When the door isopened, the tension of the chain secured to the frame pulls the slidetoward the closed end of the track, thereby preventing the removal ofthe safety chain slide from the free end of the track without firstclosing the door. A known technique of housebreakers to defeat'this typeof safety chain is to open the door and reach around the edge to attacha rubber band to the chain slide. The other end of the rubber band isattached to the door itself at a location well in from the end of theslide so that the rubber band is under tension. The housebreaker thenrecloses the door so that the tension of the rubber band pulls the slideoffthe end of the track as the closing door permits slack in the chain.The safety chain is then unfastened and the door may readily be reopenedfor entry.

The prior art track is exemplified by US. Pat. No. 2,003,473, whichshows the commonest type of safety chain'in use today. US. Pat. No.2,426,826 shows a somewhat different type of safety chain which isintended to provide security against the type of removal discussedabove, by means of a pivoted rail section which is gravity biased tooccupy a position blocking the removal of the slide. However, a burglarcould readily defeat this device by looping an additional rubber bandaround the free end of the slide to temporarily hold it in its slideremoval positionf US. Pat. No. 2,867,468 shows a vertically operatingsafety chain slide in which the track is a slot rather than a rail. theslot having an open section at the end for slide removal and a springwhich in its normal position bars the movement of the slide along theslot toward removal. Although the device requires that the spring bedepressed before the slide is moved upward to the point where removalmay be effected, the vertical orientation would permit operation'of thespring and of the chain carrying slide by a housebreaker with the doorpartially open.

SUMMARY OF THE INVENTION My invention comprises a conventional jambplate to which the security chain may be permanently fixed, and aconventional door anchorage plate carrying a slide track ofunconventional form. The slide track may be either a rail or a slot. Thesecurity chain and the slide are conventional also. The slide track doesnot have a free end, but is angled to meet the base at both ends. Anotch is provided in the track in the portion which is parallel to thedoor but meeting the portion which is angled inwardly to meet the base.The slot is shorter than that portion of the slide which lies behind thetrack to secure the slide to the track so that the slide may not simplybe pulled outwardly from the 2 is simply an offset portion of the [baseintegral with the rest of the base but offset from its plane to form thetrack rather than being formed separately with a cen tral horizontalpartition joining it to the base as shown in US. Pat. No. 2,003,473.Thus both ends of the track are part of the base, thereby making itsubstantially impossible to pivot the free end of the track away fromthe base plate by applying excessive force to the door.

DRAWINGS FIG. 1 is a front elevational view of a portion'of a door anddoor jamb with one embodiment of my invention applied thereto.

FIG. 2 is a top view of the embodiment shown in FIG. 1 applied to a doorand door jamb.

FIG. 3 is a cross-sectional view upon line 3-3 of FIG. 1.

FIG. 4 is a view similar to the view of FIG. 3 with the slide shown in adifferent position.

FIG. 5 is a front perspective view of a second embodiment of theinvention.

FIG. 6 is a detail view of the slide for theembodiment shown in FIG. 5.

DESCRIPTION My device includes a standard jamb plate 10 secured secureanchorage 12 for a security chain 14. It may also. desirably include aflange 16 for storing the slide 20 which is secured permanently to theouter end of security chain,14.

Slide 20 is provided with edge flanges 22 curved to engage the edges ofthe track for an easy sliding fit.

Door plate 30 is secured to a door in the conventional manner. The trackin this embodiment is a rail 31 which is made of the same piece of metalas door plate 30, being struck upward out of the plane of door plate '30so that main portion 32 of the :rail occupies a sepa rate parallel planein front of the door plate 30. Rail 31 is provided with an end 34 whichis mounted adjacent the door edge. Rail 31 is also provided with an end36 remote from the edge of the door. Rail 31 is full width from end 34at which it merges with the main portion of door plate 30 through mostof section 32. The termination of end portion 36 merges with base plate30 as does that of end 34. At the point where central portion 32 of rail31 meets end portion 36, notches 38 are provided in the top and bottomof the'rail 31 to a depth equivalent to the width of flanges 22 forminga narrow rail section 39 meeting end 36 and comparable in width to thespace between flanges 22. The length of notches 28 is less than thelength of flanges 22 as best shown in FIG. 3 and FIG. 4.

Because of this construction, as slide 20 is slid to the left as viewedin these drawings, it cannot be removed from the rail at any point.Flanges: 22 grip rail 31 too tightly to permit it to be turned enoughtopass through notches 38 for removal. Accordingly slide 20passes allthe way to the end 36 of the rail, at which point it is stopped bycontact with door anchorage plate 30. Thus a person seeking entry to thedoor protected by my device can attach his rubber band and secure it tothe door and can force the slide 20 to move all the way to the left, butthe slide 20 will remain securely on rail 31. When he re-opens the doorexpecting the chain to be loose, chain 14 will pull slide 20 to theright along rail 31 in the direction of jamb plate as the door opens.

Because the angle of pull is toward jamb plate 10, the slide will notpass through notches 38 and come off the rail, but will follow thecentral portion of the rail 32 and will travel to end 34, at which pointit will be again stopped by contact with door plate with the door firmlysecured against further opening. Because both ends of rail 31 are madein one piece with door plate 30 of heavy, strong metal, additionalpressure against the door will not break rail 31 free of door 30 orotherwisepermit slide 20 to come off.

When the person on the inside of the door wishes to open the door, it iseasy, with the door closed, to move slide 20 to portion 36 of the rail,at which time the slide is inclined to the same angle with respect tothe door plate as portion 36 of the rail. Flanges 22 may then exitendwise through notches 38 moving along angled end portion 36 by movingslide 20 to the right and toward the user. On the other hand, a personoutside pushing the door applies force along the taut chain 14. Such aforce pivots slide 20 to follow central portion 32 of rail 31 ratherthan permitting it to exit endwise from rail 31 byway of notches orslots 38 and narrow rail portion 39.

FIGS. 5 and 6 disclose a second embodiment of the invention in which thetrack is a slot rather than a rail.

The notched portion of the track accordingly extends outwardly from thesides of the slot instead of extending inwardly from the sides of a rail31. This embodiment includes a jamb plate 40 having an anchorage 42 forasecurity chain 44. Jamb plate 40 is attached to the jamb in-anyconventional way. A slide 46 is attached to the end of security chain 44and is shaped to slidingly engage the edges of a slot to be describedhereinafter. A slotted bracket 48 is attached to anchorage 42 andprojects upwardly therefrom for storing slide 46 when it is not in'use.

A door plate 50 is attached to the door in any con- I ventional manneradjacent to the jamb plate 10. Door plate 50 has a slot thereincomprising a central section 52, which is displaced outwardly from theplane of door plate 50 and extends parallel thereto, a jamb end section54, which extends at an angle between the jamb end of central section 52and door plate 50, and a remote end section 56, which extends at anangle between the remote end of central section 52 and door plate 50.The edges of slot sections 52, 54 and 56 and the door plate 50 areformed from the same piece of metal, the slot being formed in thematerial of door plate 50, and the edges of the slot being struckupwardly out of the plane of door plate 50 so that the central slotsection 52 occupies a separate parallel plane in front of the door plate50. The metal which defines the edges of the slot is bent over a shortdistance from the slot and forms a mound having a substantially flatcentral section 58 and two downwardly angled end portions 60 and 62which correspond respectively to angled slot sections 54 and 56.

Outwardly extending notches 64 are provided in the end of central slotsection 52 which is remote from the jamb end of the slot. The notches 64are positioned adjacent to the inner end of angled slot section 56 sothat the slide 46 can be inserted into the notches 64 at an angle aswill be described hereinafter.

The slide 46 is made up of an outer plate 66 and an inner plate 68 whichare held together in spaced parallel relationship by being attached toopposite sides of a centralsection 70. The central section 70 is smallerin width than the slots 52, 54 and 56 so as to be slideable therewithin,and the inner plate 68 has side edges 72 and 74 which extend outwardlybeyond the central section 70 to form outwardly directed flanges. Ametal loop 74 for receiving the security chain 44 is permanentlyattached to outer plate 66 by any suitable means. The distance betweenthe outer side margins of the flanges 72 and 74 is smaller than thedistance between the top and bottom edges of notches 64 but larger thanthe distance between the edges of slots 52, 54 and 56. The centralsection 70 is thicker than the metal at the edges of the slots. Thesedimensional relationships allow the slide 46 to be inserted edgewiseinto the notched portion 64 to slot 56, and slide along the slots 52, 54and 56, with the flanges 72 and 74 being engaged by the inner surface ofthe metal defining the slots and the edges of outer plate 66 beingengaged by the outer surface of the metal defining the slots. In thismanner the slide 46 embraces the sides of the slots to provide a securesliding connection for the end of security chain 44.

The length of the notched portions 64 parallel to the axis of the slot52 is enough shorter than the corresponding dimension of theslideflanges72 and 74 so that the slide flanges cannot be passed throughthe notches 64 except by being tilted and slid along the angled slotportion 56 and then returned edgewise through notches 64. Thiscorresponds to the condition illustrated for the first embodiment inFIGS. 3 and 4 wherein the notched portion 38 of the previously describedembodiment is shorter than the flanges 22 and thereby requires that theslide 20 be tilted as shown in FIG. 4 to be passed edgewise through thenotches 38. There is no difference in principle between the twoembodiments; in both cases, the track is notched to admit the slide, andthe flanges of the slide are slightly longer than the notch so as torequire the slide to be tilted to pass through the notch edgewise. Thefact that the track is a rail in one case and a slot in the other, andthat the notch is oriented inward in one case and outward in the other,does not alter the principle involved.

In order to withdraw the slide 46 through the notched portion 64, theslide must not only be tilted but also be acted on by a force componentthat extends toward the jamb in the plane of the angled slot 56. If theforce applied to the slide extends in any other direction, the slidewill move from slot 52 to 56, or vice versa, being engaged by one slotbefore disengaging from the other. Thus, the slide 46 cannot bedisengaged from the slot by the force developed by a rubber bandattached between the slide and the inner surface of the door. Such aforce would be directed slightly inwardly at the notch 64 and would onlyserve to move the slide 46 into angled slot 56 where it would come torest against the closed end of the slot. When the door was subsequentlyopened, the direction of the force applied by the security chain 44would also be directed slightly inwardly at the notch 64 and would causethe slide 46 to move from angled slot 56 into parallel slot 52.Continued force from the security chain 44 would ultimately wedge theslide 46 against the end of angled slot 54, where it would prevent thedoor from being opened any further than the small crack permitted by thelength of security chain 44. The slide 46 can, however, be easilyremoved from the inside of the door by sliding it to the notch 64,tilting it at the angle of slot 56, and. then moving it along the sameangle out of the notch.

It will thus be seen that I have provided a door safety chain which isunusually secure against housebreakers, both because of its shape andbecause of its construction of a single piece of metal for forming boththe door plate and the track. Such construction is very strong and alsogives manufacturing advantages because it is not necessary to fabricatea separate track and secure it to the door plate. The latter structurecosts more and is likely to be weaker.

While the above description is detailed and exact, it is intended forexemplification rather than limitation. The scope of my invention isdefined in the following claims.

I claim:

1. In a door security chain having a jamb plate and a door plate, asecurity chain secured to the jamb plate and a slide secured to theother end of the security chain, the improvement comprising a track onwhich said slide is slideable, said track including a center sectionsubstantially parallel to the door plate and two angled ends, a jamb endand a remote end, said ends being respectively secured to the doorplate, said slide having flanges engaging said track and having spacedmargins shaped to secure said slide to the inner side of said track inoperative position, said slide being slidevided with a notched portion,said margins of the permits them to pass through said notched portion,and said flanges being longer than said notched portion whereby saidslide must be angled! in order to pass said flanges edge first throughsaid notched portion.

2. The device of claim 1 wherein said track comprises a rail and whereinsaid notched portion of said track comprises a pair of matching notcheswhich extend inwardly from opposing edges of said track to form anarrowed portion thereof.

3. The device of claim 2 wherein said flanges are directed inwardly withrespect to said rail and wherein said flanges are spaced apart at theirmargins by a width which is smaller than the width of said rail butwhich is at least equal to the width of the narrowed portion of saidrail.

4. The device of claim 1 wherein said track comprises a slot and whereinsaid notched portion of said track comprises a pair of matching notcheswhich extend outwardly from opposing edges of :said track to form anenlarged portion thereof.

5. The device of claim 4 wherein said flanges are directed outwardlywith respect to said slot and wherein said flanges are spaced apart attheir margins by a width which is greater than the width of said slotbut which is no greater than the width of said enlarged portion of saidslot.

6. The device of claim 1 in which the track and the door plate areformed from a single piece of material. 1k l=

1. In a door security chain having a jamb plate and a door plate, asecurity chain secured to the jamb plate and a slide secured to theother end of the security chain, the improvement comprising a track onwhich said slide is slideable, said track including a center sectionsubstantially parallel to the door plate and two angled ends, a jamb endand a remote end, said ends being respectively secured to the doorplate, said slide having flanges engaging said track and having spacedmargins shaped to secure said slide to the inner side of said track inoperative position, said slide being slideable along said track to aposition of engagement with the door plate at each end without removal,the center section of said track remote from the jamb enD of said trackand adjacent said remote end section being provided with a notchedportion, said margins of the flanges of said slide being spaced apart awidth which permits them to pass through said notched portion, and saidflanges being longer than said notched portion whereby said slide mustbe angled in order to pass said flanges edge first through said notchedportion.
 2. The device of claim 1 wherein said track comprises a railand wherein said notched portion of said track comprises a pair ofmatching notches which extend inwardly from opposing edges of said trackto form a narrowed portion thereof.
 3. The device of claim 2 whereinsaid flanges are directed inwardly with respect to said rail and whereinsaid flanges are spaced apart at their margins by a width which issmaller than the width of said rail but which is at least equal to thewidth of the narrowed portion of said rail.
 4. The device of claim 1wherein said track comprises a slot and wherein said notched portion ofsaid track comprises a pair of matching notches which extend outwardlyfrom opposing edges of said track to form an enlarged portion thereof.5. The device of claim 4 wherein said flanges are directed outwardlywith respect to said slot and wherein said flanges are spaced apart attheir margins by a width which is greater than the width of said slotbut which is no greater than the width of said enlarged portion of saidslot.
 6. The device of claim 1 in which the track and the door plate areformed from a single piece of material.